LONELINESS is not good for long-distance runners, or anyone else who exercises regularly. That鈥檚 the conclusion suggested by an experiment showing that animals cope better with stress hormones released by physical activity if they have company when they exercise.
Although exercise speeds the production of new neurons, it also raises the level of the stress hormone corticosterone, which by itself has the opposite effect. Since social contact helps to reduce stress in many animals, including humans, Elizabeth Gould and fellow psychologists at Princeton University asked whether social contact affects neuron development in rats after they exercise.
Some of the rats were housed in groups of three, while the rest were housed alone. Half of each group were allowed a daily work-out on an exercise wheel, while the others got no exercise.
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The researchers measured the levels of corticosterone in the rats鈥� blood twice a day, and after 12 days they measured neuronal development in the hippocampus, the seat of learning and memory in the brain. After exercise, corticosterone levels increased by the same amount in the rats that had company as in the isolated rats. Cell growth in the brains of the group that exercised was faster than in the sedentary rats, and fastest in the rats that exercised and had company (Nature Neuroscience, DOI: 10.1038/nn1668).
鈥淭his reinforces the idea that social support helps to lessen the negative consequences of stress,鈥� Gould says.
